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Commit 24f69373 authored by David Vrabel's avatar David Vrabel Committed by Konrad Rzeszutek Wilk
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xen/balloon: don't alloc page while non-preemptible 



get_balloon_scratch_page() disables preemption so we cannot call
alloc_page() in between get/put_balloon_scratch_page().  Shuffle bits
around in decrease_reservation() to avoid this.

Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent a945928e

drivers/xen/balloon.c

+11 −12
Original line number Diff line number Diff line
@@ -398,8 +398,6 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) 
	if (nr_pages > ARRAY_SIZE(frame_list))

		nr_pages = ARRAY_SIZE(frame_list);



	scratch_page = get_balloon_scratch_page();



	for (i = 0; i < nr_pages; i++) {

		page = alloc_page(gfp);

		if (page == NULL) {
@@ -413,6 +411,12 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) 


		scrub_page(page);



		/*

		 * Ballooned out frames are effectively replaced with

		 * a scratch frame.  Ensure direct mappings and the

		 * p2m are consistent.

		 */

		scratch_page = get_balloon_scratch_page();

#ifdef CONFIG_XEN_HAVE_PVMMU

		if (xen_pv_domain() && !PageHighMem(page)) {

			ret = HYPERVISOR_update_va_mapping(
@@ -422,24 +426,19 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) 
			BUG_ON(ret);

		}

#endif

	}



	/* Ensure that ballooned highmem pages don't have kmaps. */

	kmap_flush_unused();

	flush_tlb_all();



	/* No more mappings: invalidate P2M and add to balloon. */

	for (i = 0; i < nr_pages; i++) {

		pfn = mfn_to_pfn(frame_list[i]);

		if (!xen_feature(XENFEAT_auto_translated_physmap)) {

			unsigned long p;

			p = page_to_pfn(scratch_page);

			__set_phys_to_machine(pfn, pfn_to_mfn(p));

		}

		put_balloon_scratch_page();



		balloon_append(pfn_to_page(pfn));

	}



	put_balloon_scratch_page();

	/* Ensure that ballooned highmem pages don't have kmaps. */

	kmap_flush_unused();

	flush_tlb_all();



	set_xen_guest_handle(reservation.extent_start, frame_list);

	reservation.nr_extents   = nr_pages;